Method and apparatus for adjusting pressure on scraper blades

ABSTRACT

A conveyor belt scraper blade support assembly having an elongate support bar extending transversely in excess of the width of the conveyor belt, external foundation support brackets operatively arranged to engage each end of the support bar, extensible/retractable device located between the brackets and the support bar arranged for controlled reciprocal movement of the support bar toward and away from the support brackets, spring loaded piston/cylinder assemblies mounted spatially along the length of the support bar for urging the pistons toward the conveyor belt, a blade attachment device on the piston for attaching and supporting a scraper blade thereto, a scraper blade mounted in the blade attachment device, and shock absorbing device between the brackets and the support bar.

BACKGROUND OF THE INVENTION

This invention has to do with a method and apparatus for the cleaning ofmaterial handling conveyor belts and is especially concerned with anarrangement for cleaning continuous conveyor belts for the coal handlingindustry. It is a common problem with continuous conveyor belts thatafter the material has passed the intended delivery point it issometimes carried backward on the underside of the looped belt due tomoisture and other conditions that enable the material to stick to theconveyor belt. Such a condition is not desirable because of the dirtyand dusty conditions created along the return side of the conveyor beltbut also because of the damage that can be done to the support rollerson the underside of the moving conveyor belt.

Prior art devices that have attempted to solve the problem have includedrotating brush assemblies mounted underneath and transverse to thedirection of travel of the conveyor belt and spring mounted "doctorblade" assemblies as mentioned in U.S. Pat. No. 4,598,823.

The prior art devices all appear to involve mounting a brush or a bladeon a transverse support bar that uniformly elevates or rotates so thatall the brushes or blades become tensioned or move in response to theadjustment of the bar. The problem with many of the belts in service isthat the loading of the material handled sometimes has a distributionthat is heaviest in the middle of the belt and lightest on the sides ofthe belt. The uneven loading has two effects on the conveyor belt. Firstthe belt can take on a concave curvature that then becomes convex whenthe belt is viewed from the under side of the conveyor. Further, thebelt can wear more in the middle than on the sides, causing it to bethinner in cross section in the middle. These two effects do not seem tobe taken into consideration by the prior art devices because suchdevices call for adjusting the support bar in response to the abovesituation, which in turn moves all the blades or brushes attached to thebar the same amount or places the same tension on all the blades orbrushes. Since the surface of the belt varies in location from thesupport bar due to the above conditions, the prior devices do notprovide for an individual response by a single cleaning blade to thelocation of the surface of the belt it is intended to clean.

A further problem with the devices of the prior art is that in mostcases the adjustment of the support bar must be accomplished manually atthe end of the bar as it protrudes out from under the conveyor belt. Inmost cases this will not be a convenient area for a workman eitherbecause of the debris that may accumulate in the area or because the endof the belt is located in an inaccessible area.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide an adjustablescraper blade support system for a conveyor belt operation.

It is an object of the present invention to provide a scraper bladesystem having adjustable pressure sensitivity for contact with aconveyor belt system.

It is an object of the present invention to provide apneumatic/hydraulic adjustable scraper blade system for a conveyor beltsystem.

It is a further object of the present invention to provide adjustablepressure contact between an arrangement of scraper blade assemblies anda conveyor belt system.

It is a further object of the present invention to provide a moreefficient scraper blade assembly system having both adjustable andautomatic contact tensions mechanisms.

It is a further object of the present invention to provide apneumatic/hydraulic, extension-retraction scraper blade support assemblyfor maintaining constant tension contact between the scraper blades andthe conveyor belt.

It is a further object of the present invention to provide a shockabsorbent means between the scraper blades in contact with the conveyorbelt and the transverse support bar holding the scraper blades incontact with the moving conveyor belt.

It is a further object of the present invention to provide a method foradjustable positioning scraper blades on the return side of a conveyorbelt and adjusting and automatically maintaining the pressure contactbetween the blades and the belt.

It is a further object of the present invention to provide spring loadedpiston/cylinders for supporting the scraper blades in contact with theconveyor belt and keying the pistons to prevent rotation duringoperation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a conveyor belt scraper supportassembly according to the present invention.

FIG. 2 shows a front view of the conveyor belt scraper support assemblyaccording to the present invention.

FIG. 3 shows a cross-sectional side view of the interlocking scraperblades according to the present invention.

FIG. 4 shows a cross-sectional end view of the scraper blade assemblyaccording to the present invention.

FIG. 5 shows a view 5--5 through FIG. 4 of the present invention.

FIG. 6 shows a cross-sectional view of the spring-loaded piston cylinderassembly according to the present invention.

FIG. 7 is a view 7--7 through FIG. 6 of the present invention.

FIG. 8 is a view 8--8 through FIG. 7 of the present invention.

FIG. 9 is a view 9--9 through FIG. 7 of the present invention.

FIG. 10 is a view 10--10 through FIG. 6 of the present invention.

FIG. 11 is a view 11--11 through FIG. 10 of the present invention.

FIG. 12 is a perspective view of a hold down bar and scraper bladearrangement according to the present invention.

FIG. 13 is a side view of a bushing according to the present invention.

FIG. 14 is a top plan view of the bushing shown in FIG. 13 according tothe present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

What is shown in FIG. 1 is a conveyor belt scraper assembly 10 that hasscraper blades 12 with surfaces 13 that are designed to meet with theunderside of a conveyor belt 14. The conveyor belt scraper assembly 10is comprised of a pair of opposed mounting support brackets 16 andextending between the opposing support brackets 16 a transverse supportbar 60 upon which are mounted spring loaded scraper blade supportassemblies 20. The transverse support bar 60 has opposing ends 18 and anupper surface 91. The scraper blades 12 are individually mounted in ascraper blade holder bracket 22 and are held therein by a bolt 24 thatextends through a front spring support strip 61, a perforation 26through scraper blade 12 and through the back of the support bracket 22and is fastened thereby to a threaded element 28. The front springsupport strip 61 extends in width substantially across the front face ofthe scraper blade 12. The scraper blades 12 are preferably made from a90 durometer (shore "A") urethane material or an 80 durometer (shore"A") rubber material. It is further contemplated that the scraper blademay be a one-piece unit that extends across all the scraper bladesupport brackets. The spring loaded assembly 20 consists of a cylinder30 having threads 32 that threadedly fasten to an end cap 34 withcooperatively threaded elements 36. A piston assembly 38 fits throughthe internal diameter of the cylinder 30 and has a reduced diameterportion 40 at the lower end of the piston 38. A collar 41 has an opensided perforation 43 therein so that it will slide into the reduceddiameter portion 40 and be held against longitudinal movement byshoulders 49 and 54 bounding the reduced diameter portion 40. The endcap 34 is threaded onto the cylinder 30 and holds a spring 50 captivelybetween the end cap 34 and the collar 41 on the end of piston 38. Thespring 50 will hold the piston 38 in its uppermost position and providea spring tension or pressure between the scraper blade 12 and the bottomof the conveyor belt 14. When the scraper blades are positioned intension contact with the conveyor belt 14 the spring 50 has an upper end52 which abuts the collar 41 when the collar 41 is in the reduceddiameter portion 40 on the lower end of piston 38. The transverse bar 60has opposing support plates 16 that are located at both ends 18 of thetransverse bar 60 and transversely mounted along the bar 60 are severalspatially located spring loaded scraper blade assemblies 20. On thesupport plate 16 is mounted a pneumatic or hydraulic,extension/retraction, tensioning mechanism 70 that adjusts the spatialrelationship between the transverse support bar 60 and thereby the finalcontact relationship between the scraper blades 12 and the bottom of theconveyor belt 14. Mounted on each end of the transverse bar 60 is aurethane-combination collar assembly 81. The urethane-combination collarassembly 81 has an outer flanged collar 83 and inner collar 85 withpolyurethane 87 molded in between so as to hold the outer collar 83 tothe inner collar 85. The inner collar 85 has threaded fasteners 89 thatare used to secure the collar 85 to end portion 18 of the transversesupport bar 60. Between the outer collar 83 and the inner collar 85 aurethane bonding material 87 is poured so as to unite the collars 83 and85 into a resilient, and flexible one piece unit. The reason for theurethane 87 is that when the conveyor belt 14 is moving and the supportblades 12 are in contact with the moving conveyor belt 14, it ispossible that certain vibrations or actions could produce adestabilizing effect that is transmitted to the support bar 60. Such adestabilizing effect may take the form of a sudden shock force beingtransmitted from the belt 14 to the scraper blade assembly 10 of suchmagnitude as to destroy or damage any rigidly held blades or supportbars or other mechanical structures. The urethane collar assembly 81provides a shock absorbing effect so as to reduce any mechanical shockthat can be transmitted from the moving conveyor belt 14 to the supportassembly 10. The fluid bag 70 also acts as a further shock absorbingmeans in addition to the collar assembly 81. The outer collar 83 of thecollar assembly 81 is equipped with a flange 79 that cooperates with anangle plate 77 located on the support plate 16. The flange 79 slidesinside the angle plate 77 so that in one direction it is held in placebetween the back 75 of the support plate 16 and the angle plate 77. Theflange 79 is slidingly engaged in another direction between the back 75and the angle plate 77 so that the pneumatic/hydraulic mechanism 70 isable to raise and lower the transverse support bar 60 to accommodate thedesired pressure and/or spatial distance that is desired between thescraper blades 12 and the conveyor belt 14.

The scraper blade support assembly 10 operates in the following manner:The mounting brackets 16 are used to permanently mount the supportassembly 10 on foundations (not shown) so that the support assembly 10can position the uppermost surfaces 13 of the blades 12 so that they areapproximately 1/4"-1/2" inch beneath the bottom surface of the conveyorbelt 14. The pneumatic/hydraulic support bag 70 is deflated uponinstallation so that the transverse support bar is in its lowestposition with regard to support bracket 16. The support bag 70 may beinflated by using fluids such as air, water, carbon dioxide, nitrogen,or any other suitable fluid or gas that can be supplied to the site atthe mine or other industrial location. After the initial installation aspreviously described, inflation of the pneumatic/hydraulic support bag70 brings the surfaces 13 of scraper blades 12 into engagement with thebottom-most surface of the conveyor belt 14. When this occurs, thecontact of the conveyor belt 14 with the support blades 12 force thepistons 38 down against the loaded springs in each of the assembliesthat are transversely located across the support bar 60. In thiscondition, each of the support blades 12 or each section of the supportblade 12 exerts a constant, given pressure, against the bottom of theconveyor belt 14. By controlling the pressure or the fluid in the bag70, and thereby the extension or retraction of the support bar 60, onecontrols the contact pressure between the blades 12 and the conveyorbelt 14. Should any uneven wear occur among the individual supportblades 12, or portions or scraper blade 12 then the individual springassemblies shown at 20 will adjust for each individual blade 12 orportions of scraper blade 12 and thereby compensate for uneven wear.Protector covers 610 are attached to the uppermost portions of pistons38 and extend down to the support bar 60 to protect the piston cylinderassemblies 20 from damage from the debris of the environment in whichthey will be operating.

Shown in FIG. 2 is a cross-sectional side view of the scraper bladesupport assembly 10 having the two support brackets 16 on opposing endsof the lateral support bar 60. The support bar 60 has mounted on it thespring loaded piston assemblies 20 that support the scraper blades 12.The scraper blades 12 are shown having a pressure contact with theconveyor belt 14. The support bracket 16 has mounted thereon thepneumatic or hydraulic assemblies 70 that abut with the adjustment plate102 located on the outer collar 83 that is used to transfer theinflation and deflation movements of the hydraulic or pneumatic bag 70to the support bar 60 and thereby raise or lower the position of scraperblades 12 or the tension of the scraper blades 12 against the lower sideof conveyor belt 14.

What is shown in FIG. 3 is a top view of two adjacent scraper blades 12that are slidingly inner-connected by a tongue-and-groove joint shown at13 and 15. Blade 12 is shown with a tongue element 13 along oneadjacently abutting edge of 12 and along an opposing abuttingly adjacentside is formed a groove 15 that permits tongue 13 to slide therein.

What is shown in FIG. 4 is an air or fluid bag 70 that is mounted on asupport structure 16 that is held by way of fasteners 500 and 504. Theair bag 70 may be filled with fluid through the passage shown at 502which is preferably a 1/4 npt nipple. The unitary bracket is shown at 81with the bracket consisting of an outer bracket 83 and an inner bracket85. Uniting the outer bracket 83 (which preferably is a square in crosssection) with the inner bracket 85 (which is also preferably square incross-section) is a polyurethane material 87 that is molded and bondedso that it holds the outer bracket 83 to the inner bracket 85 in aresilient manner. The polyurethane material is preferably of a materialthat is of 60 durometer (shore "A") hardness. Fasteners 89 shown locatedat 520 and 522 may be used to firmly attach to the transverse supportbar 60 that holds the scraper blade assemblies 12.

Shown in FIG. 5 is a view 5--5 through FIG. 4. The air bag 70 is shownextending between the support bracket 16 and the upper support plate 102such that the outer collar 83 is permanently welded to and abuttedagainst the upper support plate 102 that provides a support connectionto the air bag 70. The inner square collar 85 is connected by thepolyurethane 87 and telescopically engages the support bar 60 such thatany transverse vibrations, jars or sudden movements are dampened by theurethane material 87 before they can be transmitted in a damaging mannerto the other structures such as 102 and the fluid bag 70 that arenecessary for the efficient operation of the scraper blade assemblies.

What is shown in FIG. 6 is a cross-sectional view of the spring loadedpiston assembly showing the piston 38 housed within the cylinder 30 andhaving a spring 50 which abuts against the collar 41. The cylinder 30has a threaded engagement with an end cap 34 such that the spring 50 isheld captive between the collar 41 and the end cap 34. The spring 50urges the piston 38 in a full upward vertical position such that thescraper blade 12 will be held against the bottom of the conveyor belt14. The scraper blade 12 is held in the blade holder bracket 22 by afastening bolt 24 that extends through the perforation 26 in the scraperblade 12 and the perforation 27 on the angle plate 22. The fastener 24threadedly connects with the nut 28 so as to positively hold the scraperblade 12 against the angle plate 22.

What is shown in FIG. 7 is the return side of the conveyor belt 14traveling in the direction shown by the arrow and meeting upper surface13 of the with the scraper blade 12. Scraper blade 12 is held in theangle bracket 22 and fastened there by bolt 24 front spring support clip61 and nut 28. The bolt 24 has a front scraper plate 600 or front springsupport clip 61 that fits beneath the bolt head of 24 and against thefront side of the scraper blade 12. The bolt 24 has a stud 27 thatextends through the perforation 26 in the scraper blade 12 and meetswith nut 28 along the back side of the angle bracket 22. The anglebracket 22 is mounted on an upper portion 39 of the piston 38. Locatedon one side of the piston 38 is a groove 800 and which in cooperationwith key 802 helps to prevent the piston 38 from rotating. The piston 38fits down through an annular ring 900 that sits on top of bushing 918that then telescopically engages with the cylinder 30. The annular ringshown at 900 has an annular groove 910 therein. The annular groove 910is used in connection with a snap ring (not shown) to fasten theprotective boot 610 shown in FIG. 1 to the upper part of the cylinder30. The brass cylinder or bushing 918 extends down through the supportbar 60 and into the internal diameter of the cylinder 30, through whichthe piston 38 then operates. The top part of the brass bushing 918 has acollar 920 that abuts on the top part 91 of the support bar 60. Theupper portion of cylinder 30 is welded under the bottom of thetransverse support bar 60 and extends downwardly therefrom with thebushing 918 meeting with the upper portion of the tube 30 at the lowerpart of the transverse support bar. The annular ring 922 is welded tothe bar 68 and sits on top of the bushing 118 and is used to fasten thebottom of the boot cover 610. The top part of 610 is fastened to theunderside of support bracket 22. The bottom part of cylinder 30 is athreaded connection to the end cap 34 and the spring 50 is held captivebetween the end cap and the C-ring 41 where it fits into the reduceddiameter portion 40 of the piston 38.

What is shown in FIG. 8 is a view 8-8 through FIG. 7 illustrating thekeyway 800 in piston 38 that prevents the shaft 38 from rotating so thatscraper blades 12 are kept in alignment with the conveyor belt 14. Thetransverse support bar 60 has a slot 921 through its sidewall so as toallow a key 802 to be inserted therethrough. The bushing 918 will beplaced down in its position on the transverse support bar 60 so that itskeyway 921 will line up with the keyway 923 in the sidewall of thetransverse support bar 60. With the brass bushing 918 in place, the key802 may then be inserted through the sidewall slot 923 and through theslot 921 in brass bushing 918 until it projects a specified distance soas to engage the slot 800 in piston 38. The keyway 802 may then bewelded to the sidewall of the transverse support bar 60. The FIG. 7shows the key 802 that fits into the keyway 800 on shaft 38.

What is shown in FIG. 9 is the view 9--9 through FIG. 7 wherein thecollar 41 is shown around the reduced diameter section 40 of the shaft38. The collar 41 as has been previously described in FIG. 1 is fittedinto the reduced diameter portion 40 shown at FIG. 1 such that it abutsagainst the abutment surfaces 49 and 51 and allows the spring 50 to movethe piston 38 in a reciprocating vertical direction.

What is shown in FIG. 10 is a top view 10--10 of FIG. 6. This shows theupper part of the cylinder 30, the piston 38, the keyway 800 that isformed in the piston 38. The key 802 holds the piston 38 from rotatingin the transverse support bar 60 by extending through the slot in thesidewall of transverse bar 60 and through the slot 921 in bushing 918.

What is shown in FIG. 11 is the piston shaft 38 having a keyway 800through which a key 802 may hold the piston 38 from rotating. Thebushing 918 is made of brass and is placed between the upper part 91 ofthe transverse support bar 60 and the lower portion 93 of the transversesupport bar 60. The bushing 918 has a snap ring 810 that is used to holdthe bushing 805 in place. The bushing 918 has an upper flange 920 thatis used to extend over the upper surface of 91 of the support bar 60.

What is shown in FIG. 12 is a conveyor belt 14 having a conveyor beltscraper assembly 10 according to the present invention and havingengaged the scraper blades 12 on the underside of the conveyor belt 14.A hold-down bar 600 is placed against the width of the conveyor belt andis comprised of a steel structural member 612 such as a steel plate anda polyurethane material shown at 614. As the conveyor belt is moving,the hold-down bracket provides a back stop as shown at 614 such thatwhen the scraper blades 12 are elevated into position to engage thebottom side of the conveyor belt 14, the conveyor belt cannot move inthe direction of the conveyor belt 14 can be more evenly maintained.

I claim:
 1. A conveyor belt scraper blade support assembly whichcomprises:a. an elongate support bar extending transversely in excess ofthe width of the conveyor belt; b. external foundation support bracketsoperatively arranged to engage each end of said support bar; c.extensible/retractable means located between said brackets and saidsupport bar arranged for controlled reciprocal movement of said supportbar toward and away from said support brackets; d. spring loadedpiston/cylinder assemblies mounted spatially along the length of saidsupport bar for urging said pistons toward the conveyor belt; e. bladeattachment means on said piston for attaching and supporting a scraperblade thereto, f. a scraper blade mounted in said blade attachmentmeans; and, g. shock absorbing means between said brackets and saidsupport bar.
 2. The conveyor belt scraper blade support assemblyaccording to claim 1 in which said shock absorbent means comprises anattachment collar having releasable fastening means to said support bar,a mounting collar slideably attached to said support bracket and aresilient shock absorbing means attached between said attachment collarand said mounting collar.
 3. The conveyor belt scraper assemblyaccording to claim 1 in which said spring loaded piston/cylinderassemblies comprises:a. a housing for attachment to said support bar; b.a perforation through said support bar; c. a bushing seated in saidperforation with a bore for said piston; d. a piston with opposing endswith one end extending through the center of said housing and slidinglyengaged with said bore of said bushing and the other end extendingoutwardly of said support bar; e. scraper blade support bracketsattached to said other end of said piston; f. scraper blades attached tosaid support brackets; and g. spring means located in said housing andengaging said piston so as to urge said other end of said piston to itsmost outward position from said support bar.
 4. The conveyor beltscraper assembly according to claim 3 which further includesco-operating elements of key an groove means between said piston andsaid support bar to prevent said piston from rotating during operation.5. The conveyor belt scraper assembly according to claim 4 which furtherincludes cooperating elements of sliding tongue and groove means betweenadjacent scraper blades.
 6. The conveyor belt scraper assembly accordingto claim 1 which further includes a hold down bar located on theopposite side of said belt from said scraper blades and extending inexcess of the width of the conveyor belt and in contact with saidconveyor belt.
 7. The conveyor belt scraper assembly according to claim6 in which said hold down bar comprises an elongate metal body mated toa similar elongate friction resistant high molecular plastic having asurface for engaging said conveyor belt.
 8. The conveyor belt scraperblade assembly according to claim 3 in which said bushing seated in saidperforation comprises a brass material.